file.c (83f1bfd6f57c422da70d1e296df1becc35c868be) file.c (5955102c9984fa081b2d570cfac75c97eecf8f3b)
1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * file.c - operations for regular (text) files.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either

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23 *
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
25 */
26
27#include <linux/fs.h>
28#include <linux/module.h>
29#include <linux/slab.h>
30#include <linux/mutex.h>
1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * file.c - operations for regular (text) files.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either

--- 14 unchanged lines hidden (view full) ---

23 *
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
25 */
26
27#include <linux/fs.h>
28#include <linux/module.h>
29#include <linux/slab.h>
30#include <linux/mutex.h>
31#include <linux/vmalloc.h>
31#include <asm/uaccess.h>
32
33#include <linux/configfs.h>
34#include "configfs_internal.h"
35
36/*
37 * A simple attribute can only be 4096 characters. Why 4k? Because the
38 * original code limited it to PAGE_SIZE. That's a bad idea, though,

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43
44struct configfs_buffer {
45 size_t count;
46 loff_t pos;
47 char * page;
48 struct configfs_item_operations * ops;
49 struct mutex mutex;
50 int needs_read_fill;
32#include <asm/uaccess.h>
33
34#include <linux/configfs.h>
35#include "configfs_internal.h"
36
37/*
38 * A simple attribute can only be 4096 characters. Why 4k? Because the
39 * original code limited it to PAGE_SIZE. That's a bad idea, though,

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44
45struct configfs_buffer {
46 size_t count;
47 loff_t pos;
48 char * page;
49 struct configfs_item_operations * ops;
50 struct mutex mutex;
51 int needs_read_fill;
52 bool read_in_progress;
53 bool write_in_progress;
54 char *bin_buffer;
55 int bin_buffer_size;
51};
52
53
54/**
55 * fill_read_buffer - allocate and fill buffer from item.
56 * @dentry: dentry pointer.
57 * @buffer: data buffer for file.
58 *

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118 __func__, count, *ppos, buffer->page);
119 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
120 buffer->count);
121out:
122 mutex_unlock(&buffer->mutex);
123 return retval;
124}
125
56};
57
58
59/**
60 * fill_read_buffer - allocate and fill buffer from item.
61 * @dentry: dentry pointer.
62 * @buffer: data buffer for file.
63 *

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123 __func__, count, *ppos, buffer->page);
124 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
125 buffer->count);
126out:
127 mutex_unlock(&buffer->mutex);
128 return retval;
129}
130
131/**
132 * configfs_read_bin_file - read a binary attribute.
133 * @file: file pointer.
134 * @buf: buffer to fill.
135 * @count: number of bytes to read.
136 * @ppos: starting offset in file.
137 *
138 * Userspace wants to read a binary attribute file. The attribute
139 * descriptor is in the file's ->d_fsdata. The target item is in the
140 * directory's ->d_fsdata.
141 *
142 * We check whether we need to refill the buffer. If so we will
143 * call the attributes' attr->read() twice. The first time we
144 * will pass a NULL as a buffer pointer, which the attributes' method
145 * will use to return the size of the buffer required. If no error
146 * occurs we will allocate the buffer using vmalloc and call
147 * attr->read() again passing that buffer as an argument.
148 * Then we just copy to user-space using simple_read_from_buffer.
149 */
126
150
151static ssize_t
152configfs_read_bin_file(struct file *file, char __user *buf,
153 size_t count, loff_t *ppos)
154{
155 struct configfs_buffer *buffer = file->private_data;
156 struct dentry *dentry = file->f_path.dentry;
157 struct config_item *item = to_item(dentry->d_parent);
158 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
159 ssize_t retval = 0;
160 ssize_t len = min_t(size_t, count, PAGE_SIZE);
161
162 mutex_lock(&buffer->mutex);
163
164 /* we don't support switching read/write modes */
165 if (buffer->write_in_progress) {
166 retval = -ETXTBSY;
167 goto out;
168 }
169 buffer->read_in_progress = 1;
170
171 if (buffer->needs_read_fill) {
172 /* perform first read with buf == NULL to get extent */
173 len = bin_attr->read(item, NULL, 0);
174 if (len <= 0) {
175 retval = len;
176 goto out;
177 }
178
179 /* do not exceed the maximum value */
180 if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
181 retval = -EFBIG;
182 goto out;
183 }
184
185 buffer->bin_buffer = vmalloc(len);
186 if (buffer->bin_buffer == NULL) {
187 retval = -ENOMEM;
188 goto out;
189 }
190 buffer->bin_buffer_size = len;
191
192 /* perform second read to fill buffer */
193 len = bin_attr->read(item, buffer->bin_buffer, len);
194 if (len < 0) {
195 retval = len;
196 vfree(buffer->bin_buffer);
197 buffer->bin_buffer_size = 0;
198 buffer->bin_buffer = NULL;
199 goto out;
200 }
201
202 buffer->needs_read_fill = 0;
203 }
204
205 retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
206 buffer->bin_buffer_size);
207out:
208 mutex_unlock(&buffer->mutex);
209 return retval;
210}
211
212
127/**
128 * fill_write_buffer - copy buffer from userspace.
129 * @buffer: data buffer for file.
130 * @buf: data from user.
131 * @count: number of bytes in @userbuf.
132 *
133 * Allocate @buffer->page if it hasn't been already, then
134 * copy the user-supplied buffer into it.

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204 if (len > 0)
205 len = flush_write_buffer(file->f_path.dentry, buffer, len);
206 if (len > 0)
207 *ppos += len;
208 mutex_unlock(&buffer->mutex);
209 return len;
210}
211
213/**
214 * fill_write_buffer - copy buffer from userspace.
215 * @buffer: data buffer for file.
216 * @buf: data from user.
217 * @count: number of bytes in @userbuf.
218 *
219 * Allocate @buffer->page if it hasn't been already, then
220 * copy the user-supplied buffer into it.

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290 if (len > 0)
291 len = flush_write_buffer(file->f_path.dentry, buffer, len);
292 if (len > 0)
293 *ppos += len;
294 mutex_unlock(&buffer->mutex);
295 return len;
296}
297
212static int check_perm(struct inode * inode, struct file * file)
298/**
299 * configfs_write_bin_file - write a binary attribute.
300 * @file: file pointer
301 * @buf: data to write
302 * @count: number of bytes
303 * @ppos: starting offset
304 *
305 * Writing to a binary attribute file is similar to a normal read.
306 * We buffer the consecutive writes (binary attribute files do not
307 * support lseek) in a continuously growing buffer, but we don't
308 * commit until the close of the file.
309 */
310
311static ssize_t
312configfs_write_bin_file(struct file *file, const char __user *buf,
313 size_t count, loff_t *ppos)
213{
314{
315 struct configfs_buffer *buffer = file->private_data;
316 struct dentry *dentry = file->f_path.dentry;
317 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
318 void *tbuf = NULL;
319 ssize_t len;
320
321 mutex_lock(&buffer->mutex);
322
323 /* we don't support switching read/write modes */
324 if (buffer->read_in_progress) {
325 len = -ETXTBSY;
326 goto out;
327 }
328 buffer->write_in_progress = 1;
329
330 /* buffer grows? */
331 if (*ppos + count > buffer->bin_buffer_size) {
332
333 if (bin_attr->cb_max_size &&
334 *ppos + count > bin_attr->cb_max_size) {
335 len = -EFBIG;
336 }
337
338 tbuf = vmalloc(*ppos + count);
339 if (tbuf == NULL) {
340 len = -ENOMEM;
341 goto out;
342 }
343
344 /* copy old contents */
345 if (buffer->bin_buffer) {
346 memcpy(tbuf, buffer->bin_buffer,
347 buffer->bin_buffer_size);
348 vfree(buffer->bin_buffer);
349 }
350
351 /* clear the new area */
352 memset(tbuf + buffer->bin_buffer_size, 0,
353 *ppos + count - buffer->bin_buffer_size);
354 buffer->bin_buffer = tbuf;
355 buffer->bin_buffer_size = *ppos + count;
356 }
357
358 len = simple_write_to_buffer(buffer->bin_buffer,
359 buffer->bin_buffer_size, ppos, buf, count);
360 if (len > 0)
361 *ppos += len;
362out:
363 mutex_unlock(&buffer->mutex);
364 return len;
365}
366
367static int check_perm(struct inode * inode, struct file * file, int type)
368{
214 struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
215 struct configfs_attribute * attr = to_attr(file->f_path.dentry);
369 struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
370 struct configfs_attribute * attr = to_attr(file->f_path.dentry);
371 struct configfs_bin_attribute *bin_attr = NULL;
216 struct configfs_buffer * buffer;
217 struct configfs_item_operations * ops = NULL;
218 int error = 0;
219
220 if (!item || !attr)
221 goto Einval;
222
372 struct configfs_buffer * buffer;
373 struct configfs_item_operations * ops = NULL;
374 int error = 0;
375
376 if (!item || !attr)
377 goto Einval;
378
379 if (type & CONFIGFS_ITEM_BIN_ATTR)
380 bin_attr = to_bin_attr(file->f_path.dentry);
381
223 /* Grab the module reference for this attribute if we have one */
224 if (!try_module_get(attr->ca_owner)) {
225 error = -ENODEV;
226 goto Done;
227 }
228
229 if (item->ci_type)
230 ops = item->ci_type->ct_item_ops;
231 else
232 goto Eaccess;
233
234 /* File needs write support.
235 * The inode's perms must say it's ok,
236 * and we must have a store method.
237 */
238 if (file->f_mode & FMODE_WRITE) {
382 /* Grab the module reference for this attribute if we have one */
383 if (!try_module_get(attr->ca_owner)) {
384 error = -ENODEV;
385 goto Done;
386 }
387
388 if (item->ci_type)
389 ops = item->ci_type->ct_item_ops;
390 else
391 goto Eaccess;
392
393 /* File needs write support.
394 * The inode's perms must say it's ok,
395 * and we must have a store method.
396 */
397 if (file->f_mode & FMODE_WRITE) {
239 if (!(inode->i_mode & S_IWUGO) || !attr->store)
398 if (!(inode->i_mode & S_IWUGO))
240 goto Eaccess;
241
399 goto Eaccess;
400
401 if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
402 goto Eaccess;
403
404 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
405 goto Eaccess;
242 }
243
244 /* File needs read support.
245 * The inode's perms must say it's ok, and we there
246 * must be a show method for it.
247 */
248 if (file->f_mode & FMODE_READ) {
406 }
407
408 /* File needs read support.
409 * The inode's perms must say it's ok, and we there
410 * must be a show method for it.
411 */
412 if (file->f_mode & FMODE_READ) {
249 if (!(inode->i_mode & S_IRUGO) || !attr->show)
413 if (!(inode->i_mode & S_IRUGO))
250 goto Eaccess;
414 goto Eaccess;
415
416 if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
417 goto Eaccess;
418
419 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
420 goto Eaccess;
251 }
252
253 /* No error? Great, allocate a buffer for the file, and store it
254 * it in file->private_data for easy access.
255 */
256 buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
257 if (!buffer) {
258 error = -ENOMEM;
259 goto Enomem;
260 }
261 mutex_init(&buffer->mutex);
262 buffer->needs_read_fill = 1;
421 }
422
423 /* No error? Great, allocate a buffer for the file, and store it
424 * it in file->private_data for easy access.
425 */
426 buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
427 if (!buffer) {
428 error = -ENOMEM;
429 goto Enomem;
430 }
431 mutex_init(&buffer->mutex);
432 buffer->needs_read_fill = 1;
433 buffer->read_in_progress = 0;
434 buffer->write_in_progress = 0;
263 buffer->ops = ops;
264 file->private_data = buffer;
265 goto Done;
266
267 Einval:
268 error = -EINVAL;
269 goto Done;
270 Eaccess:
271 error = -EACCES;
272 Enomem:
273 module_put(attr->ca_owner);
274 Done:
275 if (error && item)
276 config_item_put(item);
277 return error;
278}
279
435 buffer->ops = ops;
436 file->private_data = buffer;
437 goto Done;
438
439 Einval:
440 error = -EINVAL;
441 goto Done;
442 Eaccess:
443 error = -EACCES;
444 Enomem:
445 module_put(attr->ca_owner);
446 Done:
447 if (error && item)
448 config_item_put(item);
449 return error;
450}
451
280static int configfs_open_file(struct inode * inode, struct file * filp)
452static int configfs_release(struct inode *inode, struct file *filp)
281{
453{
282 return check_perm(inode,filp);
283}
284
285static int configfs_release(struct inode * inode, struct file * filp)
286{
287 struct config_item * item = to_item(filp->f_path.dentry->d_parent);
288 struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
289 struct module * owner = attr->ca_owner;
290 struct configfs_buffer * buffer = filp->private_data;
291
292 if (item)
293 config_item_put(item);
294 /* After this point, attr should not be accessed. */
295 module_put(owner);
296
297 if (buffer) {
298 if (buffer->page)
299 free_page((unsigned long)buffer->page);
300 mutex_destroy(&buffer->mutex);
301 kfree(buffer);
302 }
303 return 0;
304}
305
454 struct config_item * item = to_item(filp->f_path.dentry->d_parent);
455 struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
456 struct module * owner = attr->ca_owner;
457 struct configfs_buffer * buffer = filp->private_data;
458
459 if (item)
460 config_item_put(item);
461 /* After this point, attr should not be accessed. */
462 module_put(owner);
463
464 if (buffer) {
465 if (buffer->page)
466 free_page((unsigned long)buffer->page);
467 mutex_destroy(&buffer->mutex);
468 kfree(buffer);
469 }
470 return 0;
471}
472
473static int configfs_open_file(struct inode *inode, struct file *filp)
474{
475 return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
476}
477
478static int configfs_open_bin_file(struct inode *inode, struct file *filp)
479{
480 return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
481}
482
483static int configfs_release_bin_file(struct inode *inode, struct file *filp)
484{
485 struct configfs_buffer *buffer = filp->private_data;
486 struct dentry *dentry = filp->f_path.dentry;
487 struct config_item *item = to_item(dentry->d_parent);
488 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
489 ssize_t len = 0;
490 int ret;
491
492 buffer->read_in_progress = 0;
493
494 if (buffer->write_in_progress) {
495 buffer->write_in_progress = 0;
496
497 len = bin_attr->write(item, buffer->bin_buffer,
498 buffer->bin_buffer_size);
499
500 /* vfree on NULL is safe */
501 vfree(buffer->bin_buffer);
502 buffer->bin_buffer = NULL;
503 buffer->bin_buffer_size = 0;
504 buffer->needs_read_fill = 1;
505 }
506
507 ret = configfs_release(inode, filp);
508 if (len < 0)
509 return len;
510 return ret;
511}
512
513
306const struct file_operations configfs_file_operations = {
307 .read = configfs_read_file,
308 .write = configfs_write_file,
309 .llseek = generic_file_llseek,
310 .open = configfs_open_file,
311 .release = configfs_release,
312};
313
514const struct file_operations configfs_file_operations = {
515 .read = configfs_read_file,
516 .write = configfs_write_file,
517 .llseek = generic_file_llseek,
518 .open = configfs_open_file,
519 .release = configfs_release,
520};
521
522const struct file_operations configfs_bin_file_operations = {
523 .read = configfs_read_bin_file,
524 .write = configfs_write_bin_file,
525 .llseek = NULL, /* bin file is not seekable */
526 .open = configfs_open_bin_file,
527 .release = configfs_release_bin_file,
528};
529
314/**
315 * configfs_create_file - create an attribute file for an item.
316 * @item: item we're creating for.
317 * @attr: atrribute descriptor.
318 */
319
320int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
321{
322 struct dentry *dir = item->ci_dentry;
323 struct configfs_dirent *parent_sd = dir->d_fsdata;
324 umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
325 int error = 0;
326
530/**
531 * configfs_create_file - create an attribute file for an item.
532 * @item: item we're creating for.
533 * @attr: atrribute descriptor.
534 */
535
536int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
537{
538 struct dentry *dir = item->ci_dentry;
539 struct configfs_dirent *parent_sd = dir->d_fsdata;
540 umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
541 int error = 0;
542
327 mutex_lock_nested(&d_inode(dir)->i_mutex, I_MUTEX_NORMAL);
543 inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
328 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
329 CONFIGFS_ITEM_ATTR);
544 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
545 CONFIGFS_ITEM_ATTR);
330 mutex_unlock(&d_inode(dir)->i_mutex);
546 inode_unlock(d_inode(dir));
331
332 return error;
333}
334
547
548 return error;
549}
550
551/**
552 * configfs_create_bin_file - create a binary attribute file for an item.
553 * @item: item we're creating for.
554 * @attr: atrribute descriptor.
555 */
556
557int configfs_create_bin_file(struct config_item *item,
558 const struct configfs_bin_attribute *bin_attr)
559{
560 struct dentry *dir = item->ci_dentry;
561 struct configfs_dirent *parent_sd = dir->d_fsdata;
562 umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
563 int error = 0;
564
565 inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
566 error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
567 CONFIGFS_ITEM_BIN_ATTR);
568 inode_unlock(dir->d_inode);
569
570 return error;
571}